Inspection and venting means for electric fuse devices



April 29, 1930. F. A. FELDKAMP INSPECTION AND VENTING MEANS FOR ELECTRIC FUSE DEVICES Filed Dec. 22, 1928 Patented Apr. 29, 1930 UNITED STATES PATE NT OFFICE FREDERICK A. FELDKAMP, OF NEWARK, NEW JERSEY, ASSIGNOR TO ECONOMY FUSE AND MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK INSPECTION AND VENTING MEANS FOR ELECTRIC FUSE DEVICES Application filed December 22, 1928. Serial No. 327,782.

; spection at will of thecontained fuse element or link of the device, while at the same time providing a means for safely venting the gases of combustion from the interior of the casing of the device when the fuse element is blown.

This invention has for its principal object to provide an opening in thewall of the fuse element containing casing of an electric fuse device, together with means for normally closing said opening. of such character that said opening may be uncovered at will to permit visual inspection of the contained fuse element.

This invention has for a further object to provide, in association with a wall opening of the casing of an electric fuse device, a yieldable closure which may be manually actuated to uncover the opening for inspection purposes, and which also serves as an automatic vent yieldable to internal gas pressures generated within the casing on blowing of the contained fuse element, to thereby safeguard the casing against bursting or fracture under.

the latter circumstances.

Other objects of this invention, not at this time more particularly enumerated, will be clearly understood from the following detailed description of the same.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a side elevation of an electric fuse cartridge equipped with a novel inspection and venting means illustrating one embodiment of this invention; and Figure 2 is Ia transverse section therethrough, taken on line 12-2 in said Figure 1.

Figure 3 is aside elevation of an electric fuse cartridge equipped with a modified form of inspection and venting means embodying the principles of this invention.

Figure 4: is a transverse section through an electric fuse cartridge, showing a further modified embodiment of this invention.

Similar characters of reference are employed in the above-described views, to indicate corresponding parts.

Referring to the drawings, the reference character 5 indicates the tubular casing of an electric fuse cartridge adapted to provide an interior chamber 6 through which the fuse link or element 7 extends, and having at its respective ends the metallic external contact ferrules or caps 8 to and between which said fuse link or element 7 is connected in any suitable manner. Said casing 5 is made of insulating or electrically non-conductive ma terial. Provided in the wall of said casing 5, at a point intermediatethe contact fer rules or caps 8, is an opening 9 which communicates with the interior chamber 6. Said opening 9 is of sufficient diameter to permit the fuse element or link 7', which extends through said chamber 6, to be easily observed therethrough when the same is uncovered.

In Figures 1 and'2 I have shown one form and construction of means for normally clos ing or covering said opening 9 in accordance with the principles of this invention. This form of closing or covering means comprises a base plate 10 arranged upon the outer surface of said casing 5 adjacent to said opening 9, and rigidly secured thereto by any suitable form of fastening means, such e. g. as rivets 11. Provided in connection with the forward margin of said base plate 10 are a pair of laterally spaced perforate ears or hinge knuckles 12. The reference character 13 indicates a cover or closure member adapted for pivotal connection with said base plate 10 soas to normally close over the opening 9 of said casing 5; and to this end said cover or closure member is provided on its rear end with a pair of laterally spaced perforate ears or hinge knuckles 14 for alignment with the perforate ears or hinge knuckles'1'2 of the base plate, whereby a hinge pin or pintle may be passed through these parts to thereby pivot-ally or hingedly attach the cover or closure member to the base plate. Ar- 1,

i the fuse element or link 7.

18 has a thrusting bearing on the cover or closure member 13, whereby the latter is nor mally yieldably retained in closed relation to the opening 9 of the casing 5. Said cover or closure member is preferably provided, at its free end, with an up-turned finger-piece 19, whereby the same may be conveniently engaged by the finger when it is desired to manually lift the same to uncover the opening 9 for Vision therethrough in order to inspect- The baseplate 10 and cover or closuremeniber 1 are of arcuate form in longitudinal section, and of a curvature corresponding to the curvature of the cylindrical surface of the casing 5, so that the cover or closure member will fit snugly to the surface of the casing 5, and so as to completely close the opening 9. The spring 16 should be selected to provide a tension less than the tensile strength of casin 5, and preferably sufiiciently great to hold the cover or closure member 13 closed against internal pressures long enough to permit utilization of the effects of such internal pressures. in quenching or extinguishing arcs accompanying the blowing of the fuse element or link 7, and yet not so great as to fail to yield for timely opening of the cover or closure member or gas venting operation, so as to relieve excessive internal pressures due to expansion of gases of combustion when the fuse element or link is blown.

It will be obvious that the novel construction of inspection and vent means furnishes several advantages. in use. The cover or closure member 13 may be manually opened at any time to permit inspection of the fuse element or link, so that an underwriters inspector may quickly ascertain (without removing the fuse device from its circuit com.- pleting clips) whether a proper or fraudulent fuse element or link is in use, and, furthermore, so that any one can quickly ascertain whether a given fuse element or link has blown or not. The cover or closure member 13 will automatically open so as to vent gases occurring on blowing of a fuse element or link, thus acting as a safety valve and serving to protect the casing 5 and its end ferrules against excessive internal pressures likely to burst or disrupt the former or dislodge the latter; and also said cover or closure when yieldably held in closed position by spring of selected predetermined tension will, while providing the desired safety valve or vent functioning, also permit of lesser internal pressures to be maintained, during the time of blowing of the fuse element or link, for their advantage in quickly quenching or extinguishing any arcs accompanying the blowing of the fuse element or link.

Referring now to Figure 3 of the drawings, there is shown therein a somewhat modified form and construction of closure member for the opening 9 of the casing 5. In this form, a band 20 is provided to belt or encircle the casing 5 in alignment with the opening 9 thereof, so as to tightly embrace the same in frictionally bound relation thereto against displacement. Said band 20 is provided with an opening 21 registering over the opening 9 and preferably somewhat larger in diameter than the latter. Adjacent to the margin of the opening 21 are a pair of laterally spaced.

outwardly pressed bearing portions 22. The reference character 2.3 indicates a cover or ciosure member preferably fitting said opening 21, and povided at its rearward side with laterally and oppositely projecting journal portions 24 to engage in said bearing portions 22 and thus, pivotally connect the cover or closure member 23 to said band and in operative relation to the opening 9 of the casing 5. Spring means is provided to yieldably hold said cover or closure member in closed reiation to the opening 9 of the casing 5; and the same may consist in a leaf or similar form of spring element 25 anchored in anchor yokes 2'6 pressed outwardly from the body of the band, and so that the free end of the spring may bear downwardly on the cover or closure member so as to move the same to and hold it in closed position over said opening 9. It will be apparent that, the modified form of closure member may be manually operated, and is also subject to automatic opening under the force of internal pressure, with all the advantages pointed out as to the first described embodiment of this invention.

Referring now to Figure 4, there is shown therein a simplified embodiment of the principles of this invention, the same comprising an arcuate spring cover clip 27 adapted to conform in curvature to the contour of the exterior surface of the casing 5, and of a width adapted to cover the opening 9 of the latter. This spring cover clip 27 is of a longitudinal extent exceeding one-half the circumference of the casing 5, so that it may be separably engaged over the body of the easing so as to grip and cling thereto. Said cover clip 27 may be provided, intermediate its ends, with an erteriorly projecting fingerpiece or button 28, by which it may be grasped and drawn away from the casing 5 to uncover the opening 9 for inspection purposes. It will be apparent that the gripping tension ofthe cover clip 27 may be predetermined so that the same will tend to lift relative to the opening 9 under force of internal pressure occurring in the chamber 6 of the casing 5, thus permitting the venting of gases through said opening 9 and from the chamber 6.

T is novel inspection and vent means of this invention is of especial advantage in connection with refillable fuse devices, since it permits of ready and easy inspection for the purpose of ascertaining whether or not a proper fuse element is .in use therein, and checks any temptation to replace blown fuse elements with improper conductive materials, or fuse elements of improper capacity. It will also be understood that the invention is capable of use in connection with various kinds of fuse element containers regardless of the specific form of the latter.

I am aware that various changes may be made in the general arrangements and combinations of the several devices and parts and in the details of the construction of the same, other than those already above indicated, without departing from the scope of this invention as described in the foregoing specification, and as defined in the appended claims. Hence, I do not limit this invention to the 6X act arrangements and combinations of the various devices and parts as set forth in the foregoing specification, nor do I confine myself to the exact details of the construction of said parts as illustrated in the accompanying drawings.

I claim 1. In an electric fuse device, an external casing to contain a fuse element having an opening in the wall thereof providing direct communication between the interior of said casing and the surrounding atmosphere as well as means through which said fuse element may be inspected, a cover member for said opening, and means to yieldably retain said cover member in closed position and yet free to open under internal pressure.

2. In an electric fuse device, an external casing to contain a fuse element having an opening in the wall thereof providing direct communication between the interior of said casing and the surrounding atmosphere as well as means through which said fuse element may be inspected, a cover member for said opening and spring means for yieldably holding said cover member in closed relation to said opening and yet free to open under internal pressure, said spring means having a cover closing tension less than the tensile strength of the casing.

8. In an electric fuse device, a casing to contain a fuse element having an opening in the wall thereof through which said fuse element may be inspected, a base member externally mounted on and secured to said casing, a cover member pivotally connected to said base member and disposed to close over said opening, and spring means to yieldably retain said cover in normal closed relation to said opening.

4. In an electric fuse device, a casing to contain a fuse element having external contact devices to and between which said fuse element is connected and extends, said casing having an opening in its wall through which said fuse element may be inspected, a base plate externally mounted on and secured to said casing, a cover member hingedly connected with said base plate to normally overlie and close said casing opening, and spring means to yieldably retain said cover member in closed position, said spring means having a cover closing tension less than the tensile strength of the casing.

In testimony that I claim the invention set forth above I have hereunto set my hand this 21st day of November, 1928.

FREDERICK A. FELDKAMP. 

